1. Field of the Invention
The present invention relates generally to collector apparatus which are useful in sewage treatment and liquid treatment plants and which employ chains including collector flight attachment links for carrying collector flights. More particularly, the present invention relates to a collector flight attachment link configured to have improved torsional flexibility and load bearing capabilities.
2. Reference to Prior Art
Sludge and scum collector mechanisms are commonly used in wastewater treatment tanks to scrape the settled sludge from the bottom of the tank and to skim the floating scum from the surface of the wastewater. Typically, collector mechanisms include a pair of spaced apart endless chains trained over collector chain sprockets which are mounted on cross shafts supported on the side walls of the tank, and elongated transverse collector flights supported between the chains. One of the sprockets is driven so that the chain loops revolve to provide a succession of collector flights along the bottom of the tank as well as along the surface of the water in the tank to accomplish the scraping and skimming functions. Successive collector flights push scum and sludge into collection areas of the tank for removal.
In conventional applications, each chain includes uniformly interspaced collector flight attachment links on which the collector flights are mounted. In some prior art arrangements the chains and the flight attachment links are made of metal. One such metal attachment link is illustrated in U.S. Pat. No. 3,313,422 issued Apr. 11, 1967 to Swenson which shows an attachment link consisting generally of a chain link portion provided with an upwardly projecting integral member on which a collector flight is mounted.
The combined factors of cost, weight and corrosion have created a trend in the wastewater industry to greater use of plastics and other non-metallic materials. Consequently, more recent developments in chains for wastewater treatment applications involve the use of non-metallic materials.
Flight attachment links made of non-metallic materials are well known. A sales bulletin produced by Envirex, Inc., Waukesha, Wisconsin and entitled "Conveyor Sludge Collector", Copyright 1980, discloses a flight attachment link made of acetal resin. This flight attachment link has a link portion that includes a pair of spaced apart sidebars and that can be interconnected with other chain links to form a chain, and a collector flight support portion which projects upwardly from the link portion. More particularly, the flight attachment portion includes a generally rectangular paddle plate which extends integrally from the top edges of the sidebars. A collector flight is mountable on the forwardly facing front surface of the paddle plate. Reinforcement members extend integrally from the top edges of the sidebars to the back of the paddle plate. A similarly constructed flight attachment link is shown in U.S. Pat. No. 4,663,042 issued May 5, 1987 to Rasper et al.